Polybutene-1 petroleum wax blends



United States Patent 3,338,855 POLYBUTENE-l PETROLEUM WAX BLENDS Raymond J. Kray, Berkeley Heights, N.J., assignor to Allied Chemical Corporation, New York, N.Y., a corporation of New York No Drawing. Filed Mar. 5, 1963, Ser. No. 263,067 2 Claims. (Cl. 260-285) This invention relates to petroleum wax coating compositions widely used in forming protective coatings and for other purposes.

Petroleum wax, also called paraflin wax, melting within the range of about 120 to 150 F., is widely used as a coating for wrapping paper and paperboard in the production of low-cost cartons for liquids, notwithstanding that it has a tendency to flake and crack, particularly when the paperboard is flexed or creased. Flaking and cracking impairs the vapor and moisture barrier afforded by the coating. Moreover, flaking of the wax into the contents is obviously seriously objectionable.

The blending of polyethylene with paraflin wax to produce 'a paraffin wax-containing coating of better tensile strength and ductility is known. Wax blends containing polyethylene have the serious objection that they have a markedly greater cloud point, so much so that they require application of the coating at much higher temperatures than when using paraffin wax alone. This is a serious disadvantage particularly in the coating of cardboard stocks normally carried out at temperatures of ISO-180 F. and occasionally as high as 212 F., even though the cardboard stock may be deleteriously affected at these higher temperatures.

Polypropylene, including high isotactic polypropylene, petroleum wax blends have the same objectionable characteristics as noted above in the case of polyethylene paratfin wax blends. In fact, petroleum wax polypropylene blends have appreciably higher cloud points than polyethylene paraffin wax blends.

In this specification, all percentages and parts are given on a weight basis.

In accordance with this invention, a polybutene-l resin having an isotactic content of at least 50%, preferably from 75% to 95%, a molecular weight of from 10,000 to 2,000,000, preferably 80,000 to 800,000, is blended with petroleum wax in the proportions of from 5% to 95%, preferably to 40%, resin to 95% to 5%, preferably 90% to 60%, petroleum wax.

In this specification, the expression isotactic is used in its conventional sense to mean the material in the polymer remaining after extraction with diethyl ether; the isotactic material is substantially insoluble in hexane and naphtha. The diethyl ether extraction removes the amorphous or atactic material (which is the material soluble in hexane and naphtha) and leaves a polymer containing the isotactic material.

The polybutene-l resin employed in forming the paraffin wax blends of the present invention can be prepared by polymerizing butene-l using a Ziegler type catalyst and conducting the polymerization under conditions to produce a polymer having the desired isotactic content of at least 50% and desired molecular weight of at least 10,000. Any of the known Ziegler catalysts can be used; for example, catalysts obtained by reaction between compounds of metals of group IV-A (titanium, zirconium, hafnium or thorium), V-A (vanadium, colum biumor tantalum), VIA (chromium, molybdenum, tungsten or uranium) with alkyl compounds of aluminum or a metal of group II (beryllium, magnesium, calcium, strontium, barium, zinc or cadmium). Polybutene produced by po.-. lymerization using stereospecific catalysts such as CrO on an SiO Al O support or a catalyst consisting of a promoted M00 may also be used. In all cases the polymerization must be timed and moderated to produce a polybutene-l having the desired molecular weight in excess of 10,000 and isotactic content in excess of 50% by weight. Hydrogen can be introduced into the polymerization reaction mixture to control the molecular weight and percent isotactici-ty. Polybutene-l polymers having an isotactic content of at least 50% and a molecular weight in excess of 10,000 produced by any known procedure can be used.

As an alternative to the direct polymerization of the starting butene-l, degradation of higher molecular weight polybutene-l to a desired starting molecular weight resin having an isotactic content in excess of 50% by weight can be employed. Such degradation may be catalytic, thermocatalytic or thermal. One example of such degradation is disclosed in copending application Ser. No. 152,664, filed Nov. 15, 1961, now Patent No. 3,198,779. The degraded polybutene-l of the same molecular weight as the directly polymerized butene-l gives blends of lower melt viscosities. Hence where blends having such lower melt viscosities are desired, it is preferred to employ degraded polybutene-l resins having molecular weights of at least 10,000 and isotacticities of at least 50%.

Surprisingly, polybutene-l resins having the above noted isotactic contents and molecular weights blend readily with petroleum Wax and result in coating compositions having a combination of desirable properties, not heretofore obtainable in parafiin wax coating compositions, including such compositions containing heretofore known additives or blending agents compatible with the wax. The blends of petroleum wax with polybutene-l embodying this invention surprisingly show markedly improved hardness and less tendency to flake, and this without appreciable increase in the cloud point or increase in the viscosity of the coating composition at coating tem peratures such that they require heating to a temperature appreciably higher than that required for the application of petroleum wax coating compositions consisting of petroleum wax alone.

These characteristics of polybutene-l petroleum wax blends embodying this invention, namely, that the resultant'blends have cloud points not appreciably greater than that of the parafiin wax alone and the blends at normal or usual coating temperatures have a viscosity such that they are fluid and can readily be applied at such temperatures, are important, unobvious advantages of the present invention. Curtain coaters currently and commonly employed in the coating of cardboard stock with paraflln wax and paraflin wax blends for satisfactory operation require blends which have cloud points not greatly in excess of the melting temperature of the paraffln wax alone. Moreover, it is desirable to coat at as low a temperature as possible to minimize contraction of the coating, avoid degradative effects which take place at higher temperatures, and to economize on the heat required in effecting the coating.

The polybutene-l resins herein disclosed are compatible with paraffin wax at temperatures conveniently close to the melting point of the wax itself and do not ma terially alter the coating characteristics of paratfin wax. Hence the blends of this invention can be used efiiciently in current curtain coaters.

As compared with coating compositions consisting of petroleum wax alone and blends thereof with polyethylene,.polypropylene or other heretofore known blending agents, blends of petroleum wax and polybutene-l embodying this invention exhibit superior gloss, superior hardness, less tendency to flake, increased tensile strength, increased flexural strength and increased softening point.

The marked improvement in cloud point of petroleum wax polybutene-l blends embodying this invention, as compared with blends containing the same proportion of polyethylene of polypropylene, is evident from Table I which follows. In this table the cloud point data is given in C. on a blend containing of the identified olefin polymer with 90% paraflin wax. The wax used is a typical commercial paraffin wax having an approximate melting point of 145.5 F. (63 C.) and melting within the range of l43148 F. (approximately 61-64 C.) sold by the Atlantic Refining Company as parafiin 1115 and herein referred to as parafiin 1115. This paralfin wax is also employed in all of the comparative data and in the examples given in this specification.

The improvement in melt viscosity obtained by blending a degraded polybutene-l resin as compared with the directly polymerized polybutene-l resin is apparent from Table II which follows giving the data on melt viscosities of comparative blends, each containing 20% of the indicated polybutene-l resin and 80% of the parafiin 1115.

The blending of polybutene-l with the paraffin Wax can be effected in any known or desired manner. A typical procedure for effecting such blending is described below.

A three necked flask equipped with an electric drive stirrer, a thermometer, and a nitrogen inlet tube is charged with a measured amount of paraffin wax. The wax is heated under nitrogen with moderate stirring until a clear liquid results. To the melted wax is added a charge of polybutene-l in amount herein disclosed. The mixture is heated to 140-150 C. and stirred to assist solution. The mixture can be maintained under a continuous blanket of nitrogen during the heating and stirring, if desired, and particularly when the heating is carried out under higher temperatures than 150 C. Such blanket is not necessary when operating at 140150 C. The polybutene-l charge is completely dissolved in the wax in approximately one-half hour; this is evident upon visual inspection. Desirably, however, heating of the blend is continued for an additional one-quarter hour to insure complete dissolution of the resin in the wax. The blend is thereupon allowed to cool to ambient temperature.

In this specification molecular weight values given were determined by solution-viscosity measurements (see R. Chiang, Journal Polymer Science, 28, 235, 1958). Melt viscosities Were obtained at 100 C. with a Brookfield Synchro-Lect-ric viscometer, Model R.V.T. Hardness values were obtained using a penetrometer according to ASTM D-1321-57T, using a standard needle and a weight of 50 grams. Ring and ball softening points were obtained according to ASTM E-28-58T. Cloud points were obtained according to ASTM D-97-57. Flaking propensity was indexed by measuring the amount of material sloughed 011 during a fixed degree of abrasion as disclosed in ASTM 1044-56 using a CS 17 Calabrase abrasive Wheel at 10 cycles with a 250 gram load.

TABLE II In Table III WhlCh follows are given the properties of V blends of paraflin wax and polybutene-l in the propor- Molecular Percent Melt is- Weight 189? 005m, trons indicated in this table as well as properties of the may cps. same paraffin wax alone. The blends were produced following the typical procedure hereinabove given. These D9gTadedP1Ybuime4 22x1 97 52 blends exemplify preferred embodiments of the present Directly Polymerized Polybutene-l 26x10 92 70 invention. It Wlll be appreciated, however, that this invention is not limited to these examples.

TABLE III.PART 1 Example No.

I II III IV V VI Wax 40 90 Polybutene-l 40 60 10 20 Percent Isotacticity. 73 73 9O 90 Molecular Wei ht 34, 000 34, 000 85, 000 85, 000 Hard 6. 4. 2 6. 9 5. 5 Melt Viscosity at 100 C., cps 304 2, 000 55 338 Softening Point, 77 Flaking Characteristics" 0013 001 0049 .0027 Cloud Point, C 62. 5

PART 2 Example No.

VII VIII IX X XI ML. 100 80 90 80 80 Polybutene-l 10 20 10 20 20 Percent Isotaeticity 93 92 92 61 Molecular Weight 338, 000 Hardn 8.7 Melt Viscosity at C cps.- 1, 000 Softening Point, C. 84. 78. 2 Flaking Characteristics 0036 Cloud Point, C 63.0 64.0 63.5 64. 0 65. 0

In Table IV which follows is given a comparison beextrusion in that the blend has a higher melt index (better and XVI the isotacticity of the polybutene resin was 87%, and in Example XV 40 parts resin was blended with 60 parts wax, whereas in Example XVI 60 parts resin was blended with 40 parts W-ax. Examples XVII, XVIII'an'd XIX utilized a polybutene resin having an isotacticityof 70% blended respectively in the proportions of 40, 60 and 80 parts of resin per 60, 40 and 20 parts of wax. Example XX involved a blend of 60 parts of polybutene resin having an isotacticity of 94% with 40 parts wax, and Example XXI involved a blend of 40 parts of polybutene resin having an isotacticity of 82% with '60 parts of the wax.

tween the hardness and cloud point of a paraffin wax, flow), higher tensile strength, modulus and impact atactic polybutene-1 blend and a blend embodying this strength. invention. Note that the atactic polybutene results in a The improvement elfected in abrasion-resistance in parblend having a hardness less than that of the wax whereafiin wax coatings, or reduced tendency to flake, by inas the blends of this invention result in a blend having corporating therein by blending therewith the polybutene greatly improved hardness. Note also the marked increase resins herein disclosed is demonstrated by the data conin softening point of the blend of this invention as comtained in Table VII which follows, which table gives the pared with the blends containing the atactic polybutene, results of surface abrasion tests on the indicated polyand this with practically no change in the cloud point. butene wax blends of certain of the aboxe examples and TABLE IV on the wax alone. The test procedure is disclosed in ASTM 1044-56, i.e., the same test procedure as referred oompap Example to herein for the determination of flaking propensity. The Wax XII values indicate the weight loss in grams.

TABLE VII Wax 100 so so ffilfihififiatara 3 3 33 Weight Molecular Weight. 46, 000 34, 000 Example N0, Loss, gig gg 2 3 Percent Percent Percent Molecular .0130 Cloud Point, O e.--

e1 64 e2 wax biili'e 35 w-elght The physical properties of exemplary polybutene-1 90 10 73 ,34,000 .0069 paraflin Wax blends are given in Table V which follows. 23 $8 3:838 813 In ExamplesXIII and XIV the polybutene-1 resin had an 0 0 90 510 -0049 isotacticity of 92% and was blended with the wax (paraf- 38 32; fin 1115 as noted was used in all the examples) in the 80 20 61 338.000 -0018 ratio of 20 parts resin and 80 parts Wax. In Examples XV so 20 73 34O00 0042 It will be noted from the above examples that the blends embodying this invention have softening points below 100 0., not appreciably above the softening point of the parafiin wax alone, and hence are eminently satisfactory for use in current coating machines, including curtain coaters, in which the coating is carried out at relatively low temperatures. As is evident from the data given in Table I, the cloud point of the blends of the present invention is only slightly above that of the wax alone. From Table III it is evident that the blends embodying TABLE V.PHYSICAL PROPEllgglIgliIsDgF POLYBUTENE PARAFFIN TABLE VI Polybutene Low Density Wax Blend Polyethylene Ultimate Tensile strength, p.s.i 2,130 1, 800 Modulus 24, 000 23, 000 Impact Strength 190 130 Melt Index, 190 0., 44 p.s.r 8.5 2.0

From the data in Table VI it is evident that polybutene wax blend is superior to low density polyethylene for melt this invention have a viscosity such that they are eminently satisfactory for use in available coaters which operate satisfactorily when coating materials having a melt viscosity at C. not exceeding about 2,100 cps. are employed. The resultant solidified coating is also superior to prior known wax and wax blend coatings exhibiting marked improvement in surface characteristics, particularly minimization of tendency to flaking.

That polybutene-1 resins having the relatively high isotacticity and molecular weights herein disclosed produce blends having such low cloud points is indeed surprising and unexpected. Isotactic lower alpha-olefin polymers, for example, polypropylene, result in parafiin wax blends having such high cloud points as to make the blends unsuitable for use in curtain coating machines and wherever a low cloud point is required for the production of a satisfactory coating, particularly coatings applied at temperatures below 100 C. to minimize degradation of the coating material and the substrate to which it is applied.

Surprisingly, the polybutene-l resins having the isotactic contents and molecular weights herein disclosed, notwithstanding their relatively high molecular weight and high isotactic content, are compatible with paraflin wax and when blended therewith do not impart to the blend processing difficulties in the use thereof as compared with the use of unmodified paraflin wax alone. The high molecular weight and isotacticity, unavailable in wax additives heretofore employed compatible with the petroleum wax, contribute to the coating produced by the blend embodying this invention unusual hardness, resistance to flaking, scuff resistance as well as the other desirable properties hereinabove pointed out.

While the blends embodying the present invention are eminently satisfactory for use as curtain coating melts, it will be understood that the invention is not limited thereto and these blends can be employed for other purposes wherever a paraffin wax composition of improved hardness and less flaking tendency and low cloud point finds application. Hot melt polybutene wax blends of this invention can be applied by roll coating techniques on foil, parchment, kraft, glassine, chipboard and other paper stocks to produce packaging materials having an attractive gloss and good moisture and crease resistance. With the blends of this invention the temperature to deposit an even coating of predetermined thickness need be only a few degrees above the softening point of the wax alone, which is generally in the range of 6l-64 C. Upon solidification of the coating on the substrate, the substrate has a coating on the opposite sides thereof of improved hardness as compared with such coatings consisting of the wax alone or wax with other known blending agents, improved gloss, improved tensile strength, improved impact strength and markedly improved resistance to abrasion and flaking.

Since certain changes in the petroleum wax polybutene-l blends embodying this invention can be made without departing from the scope of this invention, it is intended that all matter contained in the description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A petroleum wax blend containing as its essential constituents from about to 95% by weight of petroleum wax and from about 5% to by weight of polybutene-l resin having a molecular weight of from 80,000 to 800,000 and an isotactic content of from to said blend having a cloud point not appreciably higher than that of the petroleum wax constituent of said blend.

2. A petroleum wax blend containing as its essential constituents from about 40% to 95% petroleum wax having a melting point within the range of from to F. and from about 5% to 60% polybutene-l resin having a molecular weight of from 80,000 to 800,000 and an isotactic content of from 75% to 95 the blend having a cloud point not appreciably greater than that of the petroleum wax, and having a melt viscosity at 100 C. not exceeding 2100 cps.

References Cited UNITED STATES PATENTS 2,290,393 7/ 1942 Thomas 26028.5 2,728,735 12/1955 Anderson 26028.5 2,824,089 2/1958 Peters et a1. 26088.1

FOREIGN PATENTS 620,375 5/ 1961 Canada.

OTHER REFERENCES Gaylord et al.: Linear and Stereoregular Addition Polymers, Interscience Publishers, Inc., New York, page 129, 1959, page 663.

MORRIS LIEBMAN, Primary Examiner.

D. C. KOLASCH, B. A. AMERNICK,

Assistant Examiners. 

1. A PETROLEUM WAX BLEND CONTAINING AS ITS ESSENTIAL CONSTITUENTS FROM ABOUT 40% TO 95% BY WEIGHT OF PETROLEUM WAX AND FROM ABOUT 5% TO 60% BY WEIGHT OF POLYBUTENE-1 RESIN HAVING A MOLECULAR WEIGHT OF FROM 80,000 TO 800,000 AND AN ISOTACTIC CONTENT OF FROM 75% TO 95%, SAID BLEND HAVING A CLOUD POINT NOT APPRECIABLY HIGHER THAN THAT OF THE PETROLEUM WAX CONSTITUENT OF SAID BLEND. 